Thanks for all the feedback and suggestions.
Based on the info you have posted here, the fuel economy does seem to not be in the correct range even with my usage. So I'll do further investigation on it.
Some additional info/questions:
-Yes, the car has a VTEC engine with the conventional auto gearbox. Does anyone here drive auto?
-The spark plugs (there are four of them according to the service invoice) were replaced only last August 12, 2019. So it seems unlikely that they are the cause of the issue?
-There are two filters in the service manual that might be the air filter, can you please point out which one exactly is the air filter? There is a "dust and pollen filter" that was last replaced on August 12, 2019, and there is an "air cleaner element" that was last replaced on January 10, 2018.
-For the battery, it was last replaced on December 23, 2017, and it was last tested on June 29, 2019. The result said "good". However, I did have issues with the EPS when doing parking maneuvers:
https://clubjazz.org/forum/index.php?topic=11297.0. I didn't do anything to fix it, I just avoided the said maneuvers.
-For the binding brakes, should there something unusual that I would feel while driving? Or could the issue be there but undetected?
-For driving style, I think I do have a tendency to brake more often than necessary. I'm working on minimizing it.
-The air conditioner is always turned on when I am driving. The settings vary depending on how hot it is outside.
-The car is out of sync with the maintenance schedule. The maintenance schedule in the service manual is supposed to be every 6 months OR 10,000 km. The previous owner just had it serviced based on the number of kilometres. For example, the major service that should have been done in 72 months or 120,000 km hasn't been done yet because the car has only traveled 97,528 km in the past 12 years.
Another thing I noticed is that when going up a slope, even if it is not that steep, the car doesn't seem to want to shift. The RPM is "stuck" at around 3000-4000. I have to step hard on the accelerator to be able to get it to shift. The problem with doing that is there is a burst of power, and if there is another car upfront, I have to press the brakes again to decelerate. I wonder if these factors are negatively affecting the fuel economy as well?
I will have the car checked by a mechanic, but would be great to get your feedback on the items above.